(1) Field of the Invention
The present invention relates to sealing devices, and more particularly, relates to an inflatable sealing device for sealing a door covering an opening, such as a shutter door in an underwater vessel.
(2) Description of the Prior Art
Many submarines include an outer hull with a shutter door contoured to the outer hull. The shutter door opens and closes, for example, to allow devices to be ejected from the submarine. In existing submarines, a clearance is provided between the shutter door and the outer hull because close tolerance fits cannot be obtained in ship building without incurring expensive manufacturing costs. Furthermore, as sections of the pressure hull of the submarine are stress relieved, the connecting components move in relation to their original as built configuration. Therefore, even if a perfect tolerance fit was obtained with the original ship construction, the fit would no longer be perfect after the ship had been in operation for a period of time.
This clearance between the outer hull shutter door and the actual outer hull creates flow perturbations resulting in increased ship drag and ship flow noise. In an attempt to solve this problem, newer ships have incorporated a flexible seal around the shutter door. Theoretically, the seal would move when required by component operations and return to sealing position once the shutter was closed. This solution, however, met with a number of problems.
When the shutters were closed, the seal experienced force imbalances resulting from a lower pressure in the outer boundary layer portion of the hull as compared to the relatively stagnant sea pressure in the free flood area of the ship. As a result, the seal would open in order to relieve the pressure imbalance, and once the pressure was relieved, the seal would close again. This resulted in seal vibrations impacting the life expectancy of the seal.
Ejecting devices through the open shutter also damages the seal by flow forces and physical forces associated with the ejection process. Additional damaging forces were caused by physical interference between the seal and the moving parts of the shutter door during operation. This existing seal design was cantilevered approximately 2xc2xd in. from a solid support, and the maximum deflection stress was absorbed by the rubber seal itself. This seal design and the forces caused by moving the shutter and ejecting devices through the open shutter resulted in excessive seal failure.
A first object is the provision of a seal which is not subject to mechanical wear and tear as the door which it surrounds is opened and closed.
Another object is the provision of a seal which can seal large areas where obtaining a close fit is impossible.
Yet another object of the present invention is a seal that can be used around a shutter door to decrease a ship""s drag and hydrodynamic flow noise without being susceptible to forces that may cause excessive vibrations or seal failure.
Accordingly, the present invention features an inflatable sealing device for use with a door covering an opening in a structure. The inflatable sealing device comprises a seal retainer positioned around the opening in the structure. The seal retainer defines a retainer cavity and a slot extending from the retainer cavity toward the opening. An inflatable seal is positioned within the retainer cavity. The inflatable of seal includes a periphery defining a seal cavity and a seal tip extending from the periphery and into the slot. A pressure actuator is fluidly coupled to the seal cavity of the inflatable seal for pressurizing the seal cavity and inflating the periphery, whereby the seal tip moves through the slot and into the opening to engage and seal the door.
According to the preferred embodiment, the periphery of the inflatable seal has an elliptical cross section in a deflated state. The retainer cavity is shaped such that the periphery of the inflatable seal has a substantially circular cross section when in an inflated state. The retainer cavity preferably has a first region with dimensions generally corresponding to the elliptical cross section and a second region with dimensions generally corresponding to the substantially circular cross section. The seal periphery expands into the second region when in the inflated state and retracts into the first region when in the deflated state.
The present invention also features a sealable shutter door mechanism comprising a door together with the seal retainer, the inflatable seal, and the pressure actuator. The pressure actuator can be actuated by the door closing or actuated independently of the door closing.
In one embodiment, the pressure actuator includes a bellows fluidly coupled to the seal cavity. The bellows forces an actuating fluid into the seal cavity when the bellows is compressed. A door arm is preferably coupled to the door for compressing the bellows while closing the door. A spring positioned around the bellows uncompresses the bellows when the seal is to be deflated. The door can include a hinged door or a rotating door.